Search for dissertations about: "chemically peculiar stars"

Showing result 1 - 5 of 7 swedish dissertations containing the words chemically peculiar stars.

2. 1. Investigations of Heavy Elements in Am and HgMn stars

   Author : Linus Dolk; Atomfysik; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; HgMn stars; spectroscopy; heavy elements; Astronomi; Astronomy; Chemically peculiar stars; Am star; Fysicumarkivet A:2002:Dolk;

   Abstract : The relationship between the HgMn and Am classes of chemically peculiar stars has been investigated primarily by observing abundances of heavy elements, including Pr, Nd, Hg, Tl and Bi. The main objective of the investigation has been to gather observational evidence to provide a better understanding of the mechanisms producing the abundance anomalies of these stars, and to establish the relationship between the two classes. READ MORE

4. 2. Advances in Stellar Astrophysics from Laboratory Spectroscopy

   Author : Stefan Ivarsson; Atomfysik; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Astronomy; iridium; osmium; uranium; oscillator strengths; Spectroscopy; term analysis; line profiles; line structure; astrophysics; Sun; Chi Lupi; 17 Comae A; chemically peculiar; praseodymium; stars; space research; cosmic chemistry; Astronomi; rymdvetenskap; kosmisk kemi; Fysicumarkivet A:2004:Ivarsson;

   Abstract : Investigation of astrophysical plasmas, such as stellar atmospheres, require both knowledge of atomic structure and data. We present laboratory instruments, techniques and tools for acquisition of the data required to derive important atomic parameters such as, wavelengths, oscillator strengths and line profiles. READ MORE

5. 3. Laboratory and Stellar Spectra in High Resolution: Studies of Fe, Pt and Tl in Peculiar Stars

   Author : Gabriele Kalus; Fysiska institutionen; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; high-resolution spectroscopy; hyperfine structure; peculiar stars; iron; platinum; lead; upsilon Sagittarii; HR7775; chi Lupi; isotope shift; Atomic and molecular physics; Atom- och molekylärfysik; Fysicumarkivet A:1997:Kalus;

   Abstract : The near-infrared spectrum of upsilon Sagittarii has been registered using the SOFIN high resolution spectrometer on the Nordic Optic Telescope, La Palma. For the first time 4f-5g transitions of Fe II in any astrophysical spectrum have been identified. READ MORE

6. 4. Magnetic fields and chemical maps of Ap stars from four Stokes parameter observations

   Author : Naum Rusomarov; Oleg Kochukhov; Nikolai Piskunov; Werner Weiss; Uppsala universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; chemically peculiar stars; magnetic fields; spectropolarimetry; Doppler imaging; stellar atmospheres; Astronomy with specialization in Astrophysics; Astronomi med intiktning mot astrofysik; Astronomy; Astronomi;

   Abstract : Our knowledge of stellar magnetic fields relies almost entirely on circular polarization observations, which has historically limited our understanding of the stellar magnetic field topologies. Recently, it has become possible to obtain phase-resolved high-resolution spectropolarimetric observations in all four Stokes parameters for early-type magnetic stars. READ MORE

7. 5. Magnetic and Chemical Structures in Stellar Atmospheres

   Author : Oleg Kochukhov; Nikolai Piskunov; Georges Michaud; Uppsala universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Astronomy; chemically peculiar stars; high-resolution spectroscopy; magnetic fields; Doppler imaging; rapidly oscillating Ap stars; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik; Astronomy; Astronomi;

   Abstract : We present an investigation of the magnetic field geometries and inhomogeneous distribution of chemical elements in the atmospheres of peculiar A and B stars. Our study combines high-quality spectroscopic and spectropolarimetric stellar observations with the development and application of novel techniques for theoretical interpretation of the shapes and variability of stellar line profiles. READ MORE